The invention relates to a spinning machine, preferably an open-end spinning machine, with a plurality of spinning units, each of said units being provided with a bobbin holder for bobbins which take up the threads which are produced, and with a device traveling on tracks, said device comprising a means for removing full bobbins from the bobbin holders and a means for taking tubes to be wound from a supply station and loading them on the bobbin holders.
It is known in winding machines (Austrian Pat. No. 2 73 742) to automate bobbin changing, a magazine for empty tubes and a stationary bobbin changer being provided at each winding position. After reaching a preset diameter, the full bobbin is transferred to a conveyor belt traveling along the length of the machine, without interrupting the winding process. Simultaneously the bobbin changer provides an empty tube which is loaded on the bobbin holder. Additional means ensure that the thread, continuing to move without interruption, is then wound around the empty tube. It is only at this point that the thread is broken between the tube and the full bobbin.
A traveling bobbin changer is also known (German Offenlegungsschrift No. 2,502,946) generally designed for textile machinery. In this design, means are provided to ensure that the thread continues moving as a full bobbin is replaced by a tube to be wound. In this design, means are also provided to ensure that the full bobbin and the tube to be wound are driven during the changeover process.
It is advantageous in open-end spinning machines to have the bobbin change accomplished largely automatically. A number of devices for this purpose are known, which likewise use the basic principle known from the designs mentioned hereinabove, and exchange a tube to be wound for a full bobbin without interrupting the spinning process. In one known design (German Offenlegungsschrift No. 2,400,081), a traveling device carries the empty tubes to be exchanged for full bobbins with it. This design comprises a swivelable change arm, said arm being provided with means for opening the bobbin holder of a spinning unit, said arm also being provided with a curved panel to accept the full bobbin and to guide said bobbin to a conveyor belt. The change arm is also provided with a gripper which removes the empty tube from a magazine carried along with it and loads the tubes on the bobbin holders. This device has large dimensions owing to the magazine it carries with it, with presorting and preparation of the empty tubes being accomplished in the magazine in a complicated manner. In addition, a device of this type is very expensive. Since the movement of the thread must not be interrupted with this machine, considerable expense is required to maintain thread guidance during the changeover process. During these operations, the thread is subjected to stress in excess of normal, so that there is an increased danger of the thread breaking. If the thread should break during the replacement of the bobbin, it is extremely disadvantageous since the thread can no longer be wound on automatically because no free thread end is available which can be taken up by the tube to be wound and used for starting the winding-on process. Hence, the entire device must be designed very carefully so that it operates with extremely high precision in order to avoid breaking the thread, since a break would result in a considerable drop in production for the reasons given above.
In co-pending U.S. application Ser. No. 658,532, filed Feb. 17, 1976, now U.S. Pat. No. 4,125,990, issued Nov. 21, 1978, other bobbin changing appartus is disclosed which includes embodiments with empty spool tubes stored on the traveling device, as well as mechanisms for applying starter windings on the empty spool tubes preliminary to placing them in the bobbin holder. The present invention is a further improvement on the apparatus of this co-pending application. The subject matter of this co-pending application is hereby incorporated by reference thereto herein to the extent needed for an understanding of the present invention.
An object of the invention is to provide a traveling device for changing bobbins on an open-spinning machine, said device being simple and economical to manufacture and operating in a reliable fashion.
The invention contemplates making the device for accepting the tubes to be wound adjustable relative to the supply stations provided in fixed positions relative to each spinning unit, said supply stations holding in readiness at least one tube to be wound, said tube being provided with a thread of a length sufficient for use as a first winding for at least one winding-on process.
The invention is based in part, on recognition of the fact that there is very little difficulty associated in practice with supplying the tubes to be wound to stationary supply stations, each of which is associated with a spinning unit. This can be accomplished manually by machine operators, for example. The invention is also based, in part, on recognition of the fact that bobbins can be most easily replaced during interruption of the spinning. This has the advantage that complicated devices can be avoided which are designed to maintain thread travel during bobbin exchange. This also eliminates the risk of a thread breaking inadvertently, which interferes with automatic starting of the winding-on process. Rather, a provision is made in which the tube to be wound is provided with a first winding which permits automatic starting of the winding-on process, which must be carried out after each bobbin change.
On the whole, it may be assumed that the spinning unit, which holds a full bobbin, is also scheduled (for other reasons) for a maintenance procedure, involving in particular a cleaning of the spinning rotor. For this reason, a further configuration of the device of the invention is provided in which the traveling device is designed as a maintenance unit, said unit containing means for carrying out maintenance operations, said operations serving as a preparation for automatic winding-on. For example, it can be arranged for the means accomplishing a bobbin change to be mounted on a traveling cleaning device, said cleaning device being followed by an independent traveling device for winding-on.
These and other objects, features and advantages of the present invention will become more apparent from the following description when taken in connection with the accompanying drawings, which show, for purposes of illustration only, several embodiments in accordance with the present invention.